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Run Defense by Number of Backs, 2015

by Andrew Potter

If Monday's look at offensive rushing numbers by number of backs was instructive about the league's general trend away from multiple-back rushing sets, our look at the same numbers from the defensive side might shed some light on the reasons for that trend. As before, we're looking specifically at rushing attempts from the backfield, excluding quarterback runs and "wildcat" plays, and splitting the numbers into single- and multiple-back sets (with "back" defined as any non-quarterback in the backfield, regardless of the player's listed position).

Remember that this is from a defensive perspective, so negative DVOA numbers are a good thing (fewer yards and points allowed per play compared to an average team) -- which is good because there are plenty of negative numbers to discuss. Only three teams finished 2015 with a run defense in positive figures: Buffalo, San Diego, and Chicago. (Yes, even the historically inept 2015 New Orleans Saints defense had a negative run DVOA -- the Saints were 27th, at -2.4%.) The median run defense had a rating around -12.0%, while the median pass defense had a rating around 0.5%, because passing is generally more efficient than running on a per-play basis. You'll find a more detailed explanation of DVOA on our methods page.

As before, we'll start with the numbers before we get to the commentary:

Run Defense by Number of Running Backs, 2015

Defense

Pct 2+ RB

Rk

1 RB Rushes

2+ RB Rushes

Difference

Runs

Y/A

DVOA

Rk

Runs

Y/A

DVOA

Rk

Y/A

DVOA

Rk

OAK

39.5%

1

216

3.8

-24.1%

5

141

4.1

-9.8%

25

-0.4

-14.3%

30

SEA

39.5%

2

181

4.0

-27.7%

3

118

2.9

-31.2%

10

1.0

3.5%

18

DEN

39.2%

3

219

3.5

-26.7%

4

141

2.4

-34.2%

7

1.2

7.6%

13

MIN

37.8%

4

221

4.1

-20.1%

8

134

4.3

-3.6%

31

-0.2

-16.5%

32

JAC

37.6%

5

237

4.1

-14.1%

17

143

3.1

-20.1%

16

1.0

6.1%

16

TB

35.2%

6

267

3.8

-19.5%

10

145

3.1

-22.9%

13

0.7

3.5%

19

DAL

34.6%

7

257

4.3

-2.6%

30

136

4.3

-5.3%

29

0.1

2.6%

20

HOU

33.9%

8

216

4.3

-20.1%

9

111

3.8

-22.1%

15

0.5

2.1%

21

MIA

31.4%

9

311

4.0

-9.7%

21

142

4.2

-9.9%

24

-0.2

0.1%

22

ARI

31.3%

10

206

3.9

-34.6%

1

94

3.3

-27.8%

11

0.6

-6.8%

27

TEN

31.3%

11

263

4.2

-3.3%

28

120

3.3

-27.0%

12

0.8

23.7%

6

IND

30.9%

12

270

4.5

-11.6%

20

121

3.5

-24.1%

8

-1.0

22.5%

7

WAS

30.4%

13

247

4.4

-12.7%

18

108

5.3

-4.1%

30

-0.9

-8.6%

28

SF

29.9%

14

305

4.5

-7.2%

24

130

3.5

-7.3%

26

1.0

0.1%

23

GB

29.5%

15

244

4.2

-18.1%

12

102

4.1

-11.6%

20

0.1

-6.5%

26

ATL

29.4%

16

254

4.4

-6.7%

25

106

3.4

-20.0%

17

1.0

13.3%

11

Offense

Pct 2+ RB

Rk

1 RB Rushes

2+ RB Rushes

Difference

Runs

Y/A

DVOA

Rk

Runs

Y/A

DVOA

Rk

Y/A

DVOA

Rk

CHI

29.2%

17

260

4.3

-0.8%

31

107

4.1

-6.7%

28

0.2

5.9%

17

STL

28.6%

18

279

4.5

-14.2%

16

112

2.8

-47.5%

2

1.7

33.3%

2

CIN

28.6%

19

210

4.2

-19.3%

11

84

4.2

-14.2%

19

0.1

-5.1%

25

SD

28.4%

20

255

4.7

-2.9%

29

101

5.6

11.5%

32

-0.8

-14.4%

31

CAR

27.7%

21

227

4.4

-16.9%

14

87

2.1

-44.9%

4

2.3

28.1%

4

NO

26.7%

22

266

5.2

-3.4%

27

97

4.7

-10.1%

22

0.4

6.7%

14

KC

24.2%

23

248

4.1

-12.2%

19

79

3.0

-45.7%

3

1.1

33.5%

1

CLE

23.8%

24

307

4.8

-9.3%

22

96

3.9

-7.2%

27

0.9

-2.1%

24

DET

23.4%

25

285

4.2

-17.3%

13

87

3.5

-34.7%

6

0.8

17.4%

10

BUF

22.4%

26

260

4.7

3.4%

32

75

3.8

-22.3%

14

1.0

25.7%

5

BAL

21.8%

27

284

3.9

-21.4%

6

79

4.2

-11.0%

21

-0.4

-10.5%

29

NYG

21.6%

28

304

4.8

-7.5%

23

84

2.8

-16.4%

18

2.0

8.9%

12

PHI

21.1%

29

333

4.4

-3.5%

26

89

5.1

-9.9%

23

-0.6

6.4%

15

NYJ

20.7%

30

242

3.6

-32.6%

2

63

2.1

-64.1%

1

1.5

31.5%

3

NE

18.3%

31

286

4.0

-15.9%

15

64

3.8

-33.6%

9

0.2

17.7%

9

PIT

16.4%

32

270

4.0

-20.7%

7

53

2.9

-40.4%

5

1.1

19.8%

8

NFL

29.0%

8230

4.3

-13.5%

3349

3.7

-20.0%

0.6

7.3%

Volume Numbers

On Monday, we noted that the number of rushing plays by running backs has declined substantially over the past nine years. Even though overall rushing numbers are only down around one play per team per game, the number of rushes by running baks has now declined by around 1,200 rushes per season, or around 10 percent since 2007. The offensive figures show it very clearly, but this trend is also evident in the defensive numbers.

Before 2015, there had always been at least one defense in the league that faced multiple-back sets on at least 50 percent of opponents' running plays. In 2015, no defense even faced multiple-back sets on 40 percent of those plays. The league-leading mark of 39.5 percent against Oakland would have ranked no higher than sixth in any previous year. At the other end of the table, Pittsburgh faced the lowest percentage of multiple-back rushes on record at 16.4 percent, and the lowest 12 figures have all come in the past two seasons. The raw numbers paint the same picture: the highest number of multiple-back rushes faced, 145, is down 34 percent from a year ago, while the lowest on record is now just 53 attempts faced, down 28 percent. Teams aren't only eschewing multiple-back formations against the teams who defend them best, they're reducing their use against everybody. The worst multiple-back defense in the league has only faced multiple backs on 28 percent of running plays in the past two seasons, after being above 40 percent every year before.

The reason for this is simple: even against teams who are bad at run defense, running is almost always less efficient per play than passing, and passing is generally more efficient out of single-back sets. Running is, if not an afterthought, certainly more of a complement to passing than a fully fledged offensive philosophy for the majority of teams, meaning even a bad run defense is not the liability it once was.

That does not, however, make the quality of a team's run defense irrelevant. Offenses still strive for balance, even if balance doesn't always mean what the network analyst claims it means. Balance, in the modern NFL, has nothing to do with 50-50 splits or even 60-40 splits or any specific target number. Balance is about mixing enough running into your offense to maximize the efficiency of the offense as a whole. It means controlling the game clock as well as the scoreboard, and "staying ahead of the chains" -- maintaining progress toward the next first down and, ultimately, toward points and wins. Sometimes that means a heavy dose of the random Patriots running back du jour plowing through the Colts defense, and sometimes it means throwing the ball on a dozen consecutive plays because Gang Green has eaten your offensive line.

Every team wants to be able to do just enough of the former to avoid the need for the latter, so even pass-first teams will look to manufacture a running game. This explains why teams that grade well against single-back runs are more likely to face a higher percentage of multiple-back runs, while teams that are mediocre against single-back runs rank middle-of-the-pack in percentage faced. Good single-back run defenses see opponents load up against them in an attempt to generate a running game, while there's no need to do so against mediocre single-back run defenses.

The one apparently illogical exception to this rule is Baltimore, who were top-ten against single-back sets and bottom-third against multiple backs, but still only ranked 27th in percentage of multiple-back runs faced. This might be vestigial, however, as the Ravens were excellent against multiple-back sets in 2014.

The Jets and Steelers are also exceptions, but for very good reason: both were top-ten against single-back sets, but were historically good against multiple-back sets and as a result ranked in the bottom three for percentage of multiple-back sets faced. We'll look at just how good these teams were shortly.

We saw in the offense article that teams are continuing to running fewer multiple-back plays year after year. The defensive table suggests that the quality of the defense against single-back sets has more bearing on the percentage faced than the quality of the defense against multiple-back sets. The consistent exceptions to the trend occur when the defense is very good against single-back sets and historically good against multiple-back sets.

Efficiency Numbers

When we say run defenses these days are historically good, that is not an exaggeration. Defenses, particularly the best defenses, are now devouring multiple-back sets like never before. Each of the top eight multiple-back run defense DVOA numbers have now come in the past two seasons, and all of the top ten such teams have come since 2012.

Best Run Defenses vs. 2+ Backs, 2007-2015

Rank

Year

Team

DVOA

1

2015

NYJ

-64.1%

2

2014

ARI

-47.6%

3

2015

STL

-47.5%

4

2015

KC

-45.7%

5

2015

CAR

-44.9%

6

2014

DEN

-42.7%

7

2015

PIT

-40.4%

8

2014

NYJ

-39.8%

9

2013

CAR

-36.8%

10

2012

DEN

-36.1%

Special mention must be made of last year's New York Jets. Their DVOA of -64.1% against two-backs sets is otherworldly, the defensive equivalent of the '06 Colts or the '07 Patriots offenses. They allowed only five rushing first downs all year to multiple-back sets, and three of those five first-down plays came with under 2 yards to go. The only rushing touchdown against them from a multiple-back set was a Tom Brady fourth-down sneak, which isn't counted in these numbers. Twenty-three of the 63 multi-back plays against them (37 percent) went for no gain or a loss. Buffalo, the second-ranked DVOA rushing offense, averaging 4.9 yards per carry from two-back sets, ran 24 two-back plays against the Jets ... gaining 52 yards and two first downs, for 2.2 yards per carry. The Jets were so excellent in this one area in 2015 that the gap between them and the second-placed Rams is about the same as the gap from the Rams to the tenth-placed Seahawks.

That does not mean, however, that excellence in this category was confined to New York. Last year's fifth-best run defense against multiple-back sets was still good enough for seventh place since 2007, and would have led the league in any intervening year except 2014. It's not just the best teams who are enjoying unprecedented success against multiple-back sets either. Even the league-worst Chargers -- and they were absolutely dead last, with last year's 15.1% difference also the biggest gap between 32nd and 31st we've ever recorded -- would not have had the worst mark in any other season except 2010 (Arizona was league-worst that year at 10.7%, only slightly better than last year's Chargers), and are only the 12th-worst multiple-back run defense in the nine seasons since 2007. San Diego was the only team in the league last year to have a positive DVOA against runs from multiple-back sets, whereas every other year on record has seen at least five such teams.

It certainly looks as though offenses are naturally evolving away from multiple-back sets, and that change is being hastened by just how good defenses have become at stopping them. Granted, run defense DVOA is also improving against single-back formations, but nowhere near as dramatically as against multiple backs, and last year's leader in that category "only" has the second-best rating since 2007:

Best Run Defenses vs. 1 Back, 2007-2015

Rank

Year

Team

DVOA

1

2014

DET

-37.8%

2

2015

ARI

-34.6%

3

2015

NYJ

-32.6%

4

2014

TB

-32.1%

5

2013

NYJ

-30.8%

Arizona had the best single-back rushing defense in the league last year, forcing more turnovers (five fumbles forced, four recovered, and a safety) than they allowed scoring plays (three). They ranked tenth by percentage of plays against two-back sets in large part because their divisional opponents are three of the nine offenses most likely to use those sets, but they were about equally effective by DVOA against either single- (-34.6%) or multiple-back sets (-27.8%).

Last year's Jets also had one of the best single-back rushing defenses of the past nine years, in addition to the best-ever multiple-back run defense. Overlooked in some of the end-of-season coverage of the Saints' historic ineptitude was the fact that the 2015 Jets had the best overall run defense by DVOA since the 2000 Ravens, and the third-best of the DVOA era (1989-present) behind those Ravens and the 1991 Eagles. If the general trend is downward for rushing DVOA, last year's Jets defense is setting the pace.

As with multiple-back sets, it's not only the top teams who are historically good. The mean and median DVOA ratings against single-back sets are lower than ever before (remember, lower is a good thing for a defense), and more than a quarter of the league had a rating better than -20.0%. Whether it's a result of rule changes, restrictions on padded practice, coaching philosophies, or simply run defenders being easier to find than pass defenders, it's clear that run efficiency is continuing to decrease relative to that of the passing game. As long as rushing efficiency continues to decline, so too will rushing usage.

The NFL has changed a lot since 2007. Balance doesn't mean what it used to.

Comments

Adding yet another wrinkle. As defenses are struggling to gain traction against the pass, the run defense continues to improve(or it means nfl offenses are getting worse and worse at running the ball)

If you believed this pass happy setting would eventually turn as defenses went all out to stop the pass and traditional run based talent was now being undervalued by offenses, that simply has not happened. A trend that began in the 80s and really ramped up in 2000s simply has not reverted.

It sounds crazy, but short of getting your qbs arm to fall off : It feels like running should be strictly for milking the clock or on concede and punt plays.

I think this may come from line play, both sides. I don't have numbers but it seems that there are a lot better interior defensive lineman in the NFL right now than there have been in the past. Add in the amount of spread offense in college and the pro's and its possible that its harder to find great run blocking offensive lineman. The only way to get over -60% DVOA for a defense on runs is to destroy the line considering that FO has said that the first two yards of a run are generally the line.

I also wonder if the two back set numbers are indicative of playing the run more when there are two backs or if the pass plays in two back sets are shorter, with wheel routes out of the back field and other short plays that keeps the defense closer to the line.

This would probably take to much time but I wonder if the charters note the formation and routes run out of formations for teams.

Also, I know you explained in the first article that you didn't include Quarterback running plays but I wonder for teams with designed quarterback runs, which in many cases means that teams such as Carolina or the Jets are continuously running out of two back sets essentially when in single back and three back with two backs, effects the numbers.

Finally, I assume there weren't enough three back sets to get anything out of.

I think what you mentioned in your first paragraph probably contributes, and would add that I've seen a few people mention one effect of greater restrictions on padded practice being a decline in run blocking.

An added factor in two-back defense could be that most teams do still have a dedicated fullback, even if they only play a relatively small role on offense, and dedicated fullbacks are seldom a major receiving threat out of the backfield. Going from three-wide to two-back therefore often means putting somebody in who really isn't a pass-catcher, allowing the front seven to match up with bulk and play more aggressively.

Charters note formations and the location of the target or reception (deep left, right flat, etc.), but not really routes run as such.

I don't think QB rushing really works as the QB being considered a running back, even for most teams who frequently use their quarterbacks as rushers. In option plays you could make the case that it's effectively a two-back set, but I don't think Cam Newton lined up under center should be counted as a rusher. So somebody would have to sift through which plays should be counted and which shouldn't, which isn't impossible but is both more subjective and a lot more of a time sink than simply excluding all QB runs.

Three-back sets are lumped in with two-back, as they barely make up a dozen plays total in recent years.

Great article, this whole series has nicely illustrated the way increased passing efficiency has changed the game.

I don't think these numbers result from offenses getting worse at running the ball/run blocking or defenses getting better at stopping the run. Much has been said about spread offenses in college, but many of those offenses are still run-first operations. I think offensive linemen coming out of spread systems would be at least as poorly-equipped to handle NFL pass blocking duties because those college spread systems run so many quick screens and automatic reads. When you run the ball you still have to beat the guy in front of you, although I recognize that blocking schemes can vary widely.

Obviously the increase in passing efficiency alone drags on run DVOA, but I wonder if another explanation might be that, as teams rely more and more on passing as part of their base offense, a relatively greater percentage of run plays exist as filler, like run out the clock situations, as opposed to when the offense is going full-out on every possession.

One final thought—a few years ago DVOA was changed to normalize to individual seasons, I believe in part because of the way the offensive environment was changing. Seems like this trend has only accelerated since then. I wonder if these run defense DVOA numbers would look less historic if they were calculated the old way.